User Guide
Mac Pro Troubleshooting — Symptom Charts 157
Replace the processors4.
Replace the logic board 5.
Replace the power supply 6.
Fans
Individual fan failure
Verify fan is properly connected.1.
Verify all other fans are working properly. If all fans seem to have failed, the problem is most 2.
likely not the fans. Reset the logic board to see if this resolves this problem.
Replace fan3.
Replace logic board 4.
Fans run at high speed (computer may shut down or may just hang and not shut
down as a result)
Check for proper ventilation around the exterior of the computer. 1.
Remove the computer’s side access panel and observe the diagnostic LEDs, specically LED 2.
4 and LED 5 (the CPU A and B Overtemp LEDs). Refer to “Diagnostic LEDs” in this chapter for
more information on how to locate and interpret these LEDs. If either LED is ashing, it may
indicate an initial processor over-temperature condition. If either LED is solidly on, it may
indicate a chronic processor over temperature condition.
Verify proper processor heat sink installation (see the take apart section for more information 3.
on heat sink installation).
Verify all thermal sensors and their cables are properly connected, especially the ambient 4.
temperature sensor board.
Verify all fans are operating properly and are unobstructed, especially the front intake fan.5.
Verify that the proper type of memory is installed. (See “6. Memory” in the Take Apart chapter
for more information.)
Replace power supply.7.
Computer performance seems sluggish or slow, or computer is completely hung
Start up the computer from a known-good volume, such as its Installation disc, or an external 1.
hard drive, to isolate the issue to software or hardware. If the computer seems to perform
adequately when booted in this way, troubleshoot as a software issue. If the computer
continues to perform sluggishly when booted this way, continue following the steps below.
Run Apple Service Diagnostic to verify hardware is functional. Address any diagnostic failures 2.
as necessary.
Check for proper ventilation around the exterior of the computer. 3.